In conditional access systems, security information such as control words, or information used to derive control words, are inserted into services to allow authorized users to watch or listen to received content on numerous different user devices. Control words may be used to descramble a scrambled content stream (e.g., a channel) at a receiver device such as a gateway, computer, tablet, and/or other computing device. At periodic times, updated or new security information needs to be forwarded to user devices so that they may continue to consume authorized content.
In providing such services, encryption and decryption techniques may be implemented to prevent unauthorized access to services. One encryption and decryption technique for a media stream of a service may include the use of control words and associated ECMs (Encryption Control Messages). Accordingly, in one example, an increase in an amount of content being streamed results in the control words and ECMs being repeated at short intervals during a single cryptographic period, thereby consuming additional bandwidth.
In current conditional access systems, utilized bandwidth is increased just prior to transition points between different content streams as the number of ECM messages is doubled, thereby increasing overall bandwidth usage at potentially unpredictable times. The increasing of the number of total ECM messages just prior to the transition point may begin at approximately five minutes prior to a transition point between content streams. The increase in the total number of ECM messages just prior to a transition point is due to the transmission of “new” ECM messages containing security information for the next content stream to be delivered along with the current ECM messages for the content stream being currently delivered. The new security information is forwarded in advance so that devices may decrypt the new content timely upon content delivery. However, such an increase in ECM bandwidth decreases the overall bandwidth available for consuming services which impacts the user viewing experience for the delivered content stream. A more efficient bandwidth utilization method is needed for systems that exercise control over or provide access to distributed electronic content.